The present invention relates to an earphone antenna for portable wireless equipment worn on the human body during use.
Portable wireless equipment worn on the human body during use, such as a pager, a radio receiver or a liquid crystal television receiver, has heretofore used an earphone antenna which uses, as an antenna, signal wires for transmitting audio signals to a rod antenna and earphones (Japanese Patent Application Publication No. 2003-163529).
However, the portable wireless equipment using a rod antenna or an earphone antenna has drawbacks that when the equipment is used in the state of being worn on the human body, the performance of the antenna is remarkably degraded due to the wear of the equipment on the human body, so that it is difficult to obtain satisfactory reception sensitivity in the case of television broadcasting which handles signals containing a large amount of information such as video images.
In particular, the earphone antenna which uses, as an antenna, signal wires for transmitting audio signals to earphones has a drawback that since the earphones or the signal wires come in direct contact with the human body, the human body greatly influences the wireless equipment through the antenna and greatly impairs stability of reception.
Television broadcasting in Japan, for example, uses the VHF band of 90–108 MHz (1–3 ch) and 170–222 MHz (4–12 ch) and the UHF band of 470–770 MHz (13–62 ch). Accordingly, liquid crystal television receivers for receiving television broadcasting need to receive high frequency signals over an extremely wide band of 90–770 MHz, but the existing rod antenna and earphone antennas are inferior in performance to fixed types of antennas and have extreme difficulty in obtaining satisfactory sensitivity in the necessary frequency range.
In addition, the existing earphone antennas are remarkably low in sensitivity because they make use of ordinary earphones, or have a special structure in which a separate antenna wire is inserted between signal wires of earphones, or have an unremovable structure because of integral molding.
The present invention has been made in view of the above-mentioned drawbacks, and intends to provide an earphone antenna able to alleviate the influence of the human body and ensure stability of reception as well as to use replaceable earphone units.